Injection foam molding machine

A method for controlling an actual thickness of a foamed and molded product formed by a core back operation in which a movable mold platen is moved away from a fixed mold platen using both of mold opening and closing actuators and core back devices which are connected to the movable mold platen, each of the core back devices including a motor, a ball screw shaft of which one end is connected to the motor and the other end is a free end, and a nut screwed onto the ball screw shaft, the method comprising:

• operating each of the mold opening and closing actuators and the core back devices independently so that positions of shafts of the mold opening and closing actuators are set to core back target completion positions of the shafts and so that positions of the ball screw shafts of the core back devices are set to core back target completion positions of the ball screw shafts to move the nut to push an end surface of a contact support, the contact support being disposed so that the end surface of the contact support faces to an end surface in an axial direction of the nut and having a hollow portion along the axial direction into which the other end of the ball screw shaft is capable of being inserted, wherein
• the core back target completion position is preliminarily determined for each of the shaft of the mold opening and closing actuators and each of the ball screw shafts of the core back devices by:
• calculating or measuring at least one of a shape of the foamed and molded product, an opening speed of the movable mold platen, and a stop position of the movable mold platen;
• calculating a core back target stop reference position value and a stop position offset value for each of the shafts and each of the ball screw shafts based on a result of the calculation or measurement;
• and
• obtaining the core back target completion position of each of the shafts and each of the ball screw shafts by adding the stop position offset value to the core back target stop reference position value or subtracting the stop position offset value from the core back target stop reference position value.